Process of cleaning emulsions off films



Patented Oct. 23, 1951 OFFICE PROCESS OF CLEANING EMULSIONS OFF FILMS Anthony John Stybel, Bayonne, N. J.

No Drawing. Application June 11, 1947, Serial No. 754,051

4 Claims.

This invention relates to a process for cleaning the emulsion off of films, and especially, in which the films are passed successively through solutions in the treating of the films, and in which one of the solutions stops the action of the bleaching agents employed in the previously used solutions, the object of the invention being to permit the films to be passed at a high rate of speed, such as 25 feet per minute and to economically accomplish the purposes of the invention efficiently and expeditiously. However, the rate of speed depends upon the size of the tanks.

Another object of the invention is to treat films with solutions or formulas therefor, by which the emulsions may be cleaned off films expeditiously, and in which the quantity of water may be varied or added more-or-less, as found desirable, and wherein the silver salts will settle at the bottom of one of the solutions in impure form, although bleaches may be used instead of sodium hypochlorite therein and the solution drained off from the impure silver salts, for continued use or reuse.

In accordance with the present invention, the films are passed successively in the following solutions:

(1) Water, at 60 F. to 110 F., one (1) to two (2) gallons, depending upon the size of the tank available.

(2) Sodium hypochlorite solution 60 F. to 100 F. two (2) gallons or sodium hypochlorite powder one (1) pound and one (1) gallon of water at 60 F. to 100 F. in which the solution or powder is thoroughly dissolved.

(3) Hypochlorous acid one-half gallon to two (2) gallons of water at 60 F. to 100 F.

(4) Sodium sulfite one (1) pound to two (2) gallons of water at 60 F. to 100 F.

(5) By running water two (2) gallons, are contained in suitable tanks which are acid resistant, a rate of speed being 25 feet per minute through which the films are successively passed in the order stated, the rate of speed depending upon the size of the tanks.

Water can be added more-or-less, in solutions 2, 3 and 4.

In the solution 2, the impure silver salts will settle at the bottom of the solution and the solution may be drained oil for continued or reuse.

In solution 2, instead of sodium hypochlorite, chlorine bleaches may be used and substituted therefor.

Solution 1 is to swell the emulsions on the films at a temperature of 60 F. to 110 F.

Solution 2 is the most important part, because the emulsion comes off in this solution. The

sodium hypochlorite is an active bleaching agent and acts on the emulsion on the films but the solution 4 or sodium sulfite produces an interaction between the solutions and on the films, in that the solution 4 stops the action of the bleaching agent and fixes the progress and action thereof. When the emulsion starts to appear white in color, this means that the solution 2 has weakened and is drained ofi and replaced by a new solution. The solution which has been drained is put aside to settle because the silver salts will settle at the bottom of the solution, for continued use or reuse thereof.

The solution 3 or hypochlorous acid is also an active bleaching agent and acts on the excess of emulsion some of which may be left on the films when the films come out of the solution 2. Also, chlorine water and chloride of lime can be used instead of the hypochlorous acid in the same proportions as a bleaching agent, because they are also active bleaching agents, especially at the temperatures indicated.

The solution 4 or sodium sulfite, is to stop the active bleaching agents reaction on the films, especially when the proper results are attained.

The water, running, in number 5 step, is used to wash the films because the films contain salts from solutions, 2, 3 and 4 and the tank containing the running water must be supplied continuously with the water to present a clear and clean solution. The films are then dried for five minutes at F. and are ready for reuse. This process does not damage the films in any way.

It will thus be seen that I have provided an expeditious treatment for films for removing the emulsion coating therefrom, which may be speedily and efficiently operated, so that the films are ready for use when dried after treatment.

1 do not desire to limit to the exact proportions stated and as pointed out, the temperatures and proportions are critical, in order to permit the expeditious treatment of the films, for removing the emulsions therefrom, as described. The chlorine bleaches can be used instead of sodium hypochlorite, chlorine water, chloride of lime or the like in the same proportions with the water as stated in connection with the hypochlorous acid, producing active ingredients or bleaching agents, especially at the temperatures indicated which are bound to give the best results. Therefore I do not desire to be limited to the exact proportions stated, but reserve the right to vary the 3 same within the scope of the invention as claimed.

Having described the invention, what is claimed as new is:

1. A process of cleaning and removing emulsions of silver salts in gelatin from photographic films comprising first passing the film through a first water bath to swell the emulsions on the film, then passing the film through an aqueous sodium hypochlorite solution to precipitate the 10 silver salts as silver chloride, thereafter passing the film through an aqueous hypochlorous acid solution to complete the precipitation of the silver salts as silver chloride, then passing the film through an aqueous sodium sulfite solution, and finally washing the film in water.

2. The process of claim 1 wherein said first water bath is maintained at a temperature of 60 to 110 F. and the remainder of the solutions are maintained at a temperature of 60 to 100 F.

3. The process of claim 1 wherein the ingredients of said solutions are employed in the following proportions: 1 pound sodium hypochlorite to 1 gallon of water; gallon hypochlorous acid to two gallons of water; and one pound of sodium sulfite to 2 gallons of water.

4. The process of claim 3 wherein said first water bath is maintained at a temperature of 60 to 110 F. and the remainder of the solutions are maintained at a temperature of 60 to 100 F.

ANTHONY JOHN STY BEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A PROCESS OF CLEANING AND REMOVING EMULSIONS OF SILVER SALTS IN GELATIN FROM PHOTOGRAPHIC FILMS COMPRISING FIRST PASSING THE FILM THROUGH A FIRST WATER BATH TO SWELL THE EMULSIONS ON THE FILM, THEN PASSING THE FILM THROUGH AN AQUEOUS SODIUM HYPOCHLORITE SOLUTION TO PRECIPITATE THE SILVER SALTS AS SILVER CHLORIDE, THEREAFTER PASSING THE FILM THROUGH AN AQUEOUS HYPOCHLOROUS ACID SOLUTION TO COMPLETE THE PRECIPITATION OF THE SILVER SALTS AS SILVER CHLORIDE, THEN PASSING THE FILM THROUGH AN AQUEOUS SODIUM SULFITE SOLUTION, AND FINALLY WASHING THE FILM IN WATER. 